Pendulum impact tester



NOV. 6, 1945. v I G R 2,388,246

PENDULUM IMPACT TESTER Filed May 11, 1945 34 26 l p a? INVENTOR.

AW /7w" J. Berger ATTORNEY Patented Nov. 5, 1945 PENDULUM IMPACT TESTER Y Arthur J. Berger, New York, N. Y. l

j I Application Ma 11, 1945, Serial No. 59 .180 1 30mins. (01. 73-12) (Granted under the act of March 3, 1883, as

amended April 30, 1928;379 6. 757) This invention relates to an apparatus for testing resistance to impact of brittle materials such as chinaware, glassware and plastics.

In previous testing methods the test sample was placed in line with a pendulum type hammer. The hammer was then raised and'released manually, striking the sample at the bottom of its downward swing. The sample was repeatedly struck, at the same point, until failure occurred, with blows of increasing force. The force of the blow was determined by the are through which the hammer was raised. By this method, however, it was difiicult to obtain reproducible results, due mainly to the fact that one of the major controlling features of the test, i. e. the release of the pendulum, was performed manually.

It is an object of this invention, therefore, to provide an apparatus for obtaining uniform release of the pendulum hammer.

It is a further object to provide electro-magnetic means for holding and releasing the pendulum hammer.

Another object is to provide adjustable electro-magnetic means for holding and releasing the pendulum hammer, which are movable in the same plane and in the same are as the said pendulum hammer.

Further objects and advantages of this invention, as well as its construction, arrangement and operation will be apparent from the following description and claims in connection with the accompanying drawing, in which Figure 1 is a side. elevation of the testing apparatus embodying this invention, and

Figure 2 is a sectional view taken on the line 2--2 of Figure 1.

Referring to the drawing in detail, Figure 1 shows a base plate 2| having a holder 22 slidably mounted thereon for securing the test sample, such as sauce;- 23, in the proper position. A support rod 24 is mounted vertically upon the other end of base plate 2! slightly off center, as shown in Figure 2, so that an impact hammer 25 may swing through the center plane.

The impact hammer 25 of magnetic material is fixed to pendulum rod 26 which is pivotally attached at 21 to an extension 28 upon crossrod 29 (Fig. 2). The crossrod 29 is secured to the support rod 24 by clamp 30.

A dial 3| is also fixed to the crossrod 29 by means of dial holder 32 and set screw 33 (Figure 2). This dial 3| is graduated, as at 34, and is calibrated to indicate the force developed by the pendulum hammer as it swings through an are pact hammer 25 is placed determined by the relation of thependulum ro'd 26 to the marks 34 upon the dial.

An important feature of the present invention s the provision of an electromagnet 35 for holding and releasing the impact hammer 25. This magnet 35 is adjustably mounted by means of a clamp or similar device 36 upon a support arm 31 which is in turn adjustably held at its upper section by means ofa friction clamp 38 to the crossrod 29. At the upper end of the support arm 31 is a counter balance 39 to assist in moving and holding the magnet in operating position. The support arm 3'! pivots approximately aroundthe same axis as the pendulum rod 26. Thus the electro-magnet may be readily aligned for desired energy of impact and plane of swing.

The electro-magnet 35 is connected by means of Wires 40 through a switch box 4| to a suitable source of energy. By actuating the switch lever 42 the electro-magnet 35 is energized or deenergized as desired.

In operation, the test sample 23 is placed against the holder 22. The electro-magnet 35 is energized by closing the switch lever 42. The imagainst the magnet 35 which is moved until the hammer 25 is in the desired position to obtain a predetermined energy of impact as indicated by the relation of the pendulum rod 26 to the dial 3|. The electro-magnet 35 is then deenergized by opening the switch lever 42, allowing the hammer 25 to fall and strike the test sample 23. Changes in energy of impact are obtained by shifting the magnet 35 and hammer 25 in the arc of swing, no change in the relation between the magnet 35 and the hammer 25 occurring because they pivot about a common axis. Due to the counter balance 39 the electro-magnet 35 will retain its adjusted position by means of the friction clamp 38 without the use tional locking means.

By the present invention, successive tests are run with an accurate reproduction in arc of swlng, point of impact, and energy of impact of l the pendulum hammer, thereby giving true and comparable results.

It is to be understood that various modifications and changes may be made in this invention without departing from the spirit and scope thereof as set forth in the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

of addidulum type hammer of magnetic material pivot ably attached to a support therefor,-the--improve;--

ment comprising an arm pivotably attached at its upper midsection to the said support,- a -c1amp adjustably securing said arm.to said support-man electromagnet attached to the lower end of the said arm and lying in the arc of swing ofthesaid hammer, a counterbalance mounted upyomthe upper end of the said arm, meanstconnecting said:

electromagnet to a source of energy, and switch means:v in said 1 connecting; means; whereby: the

said electromagnet may be selectively energized or deenergized.

3. In an impact testing machine having a pendulum type hammer of magnetic material piv-' otably attached to a support therefor, the improvement comprising an electromagnet adjustably supported in the arc of swing of the said hammer hm means of an arm zpivotably attached at its upper section by'a friction clamp to the said support so as to yieldably rotate about approximately the same axis as the said pendulum hammer; thersaid arm having a counterbalance mounted upon its upper end, and circuit means conneetedwith the said electromagnet for se- Iectively, energizing and deenergizing the said electromagnet whereby the said hammer may be selectively held and released by the said electromagnet,

ARTHUR J. BERGER. 

